Film thickness prediction in elastohydrodynamically lubricated elliptical contacts

Abstract

This paper analyses the minimum and central film thickness evolution of elastohydrodynamically lubricated contacts, from circular to wide elliptical contacts. It is shown that already for moderate ellipticity, the minimum film thickness is found on the centre-line of the contact, rather than in the side lobes as for the circular contact. In such cases, the film thickness can be accurately predicted from an equivalent line contact, defined as the line contact with the same Hertzian pressure, radius of curvature, and speed and oil parameters. In this paper, a formula is presented to predict the central film thickness in elliptical contacts using prediction formulas for the line and circular contacts as limiting cases, and the results of numerical calculations to fit the film thickness variation with ellipticity. The formula gives an accurate prediction of the central film thickness over the entire ellipticity regime.